stack-orchestrator/docs/arista-eos-reference.md

Arista EOS Reference Notes

Collected from live switch CLI (? help) and Arista documentation search results. Switch platform: 7280CR3A, EOS 4.34.0F.

PBR (Policy-Based Routing)

EOS uses policy-map type pbr — NOT traffic-policy (which is a different feature for ASIC-level traffic policies, not available on all platforms/modes).

Syntax

! ACL to match traffic
ip access-list <ACL-NAME>
   10 permit <proto> <src> <dst> [ports]

! Class-map referencing the ACL
class-map type pbr match-any <CLASS-NAME>
   match ip access-group <ACL-NAME>

! Policy-map with nexthop redirect
policy-map type pbr <POLICY-NAME>
   class <CLASS-NAME>
      set nexthop <A.B.C.D>          ! direct nexthop IP
      set nexthop recursive <A.B.C.D> ! recursive resolution
      ! set nexthop-group <NAME>      ! nexthop group
      ! set ttl <value>               ! TTL override

! Apply on interface
interface <INTF>
   service-policy type pbr input <POLICY-NAME>

PBR set options (from CLI ?)

set ?
  nexthop        Next hop IP address for forwarding
  nexthop-group  next hop group name
  ttl            TTL effective with nexthop/nexthop-group

set nexthop ?
  A.B.C.D          next hop IP address
  A:B:C:D:E:F:G:H  next hop IPv6 address
  recursive        Enable Recursive Next hop resolution

No VRF qualifier on set nexthop. The nexthop must be reachable in the VRF where the policy is applied. For cross-VRF PBR, use a static inter-VRF route to make the nexthop reachable (see below).

Static Inter-VRF Routes

Source: EOS 4.34.0F - Static Inter-VRF Route

Allows configuring a static route in one VRF with a nexthop evaluated in a different VRF. Uses the egress-vrf keyword.

Syntax

ip route vrf <ingress-vrf> <prefix>/<mask> egress-vrf <egress-vrf> <nexthop-ip>
ip route vrf <ingress-vrf> <prefix>/<mask> egress-vrf <egress-vrf> <interface>

Examples (from Arista docs)

! Route in vrf1 with nexthop resolved in default VRF
ip route vrf vrf1 1.0.1.0/24 egress-vrf default 1.0.0.2

! show ip route vrf vrf1 output:
! S 1.0.1.0/24 [1/0] via 1.0.0.2, Vlan2180 (egress VRF default)

Key points

• For bidirectional traffic, static inter-VRF routes must be configured in both VRFs.
• ECMP next-hop sets across same or heterogeneous egress VRFs are supported.
• The show ip route vrf output displays the egress VRF name when it differs from the source VRF.

Inter-VRF Local Route Leaking

Source: EOS 4.35.1F - Inter-VRF Local Route Leaking

An alternative to static inter-VRF routes that leaks routes dynamically from one VRF (source) to another VRF (destination) on the same router.

Config Sessions

configure session <name>           ! enter named session
show session-config diffs          ! MUST be run from inside the session
commit timer HH:MM:SS              ! commit with auto-revert timer
abort                              ! discard session

From enable mode:

configure session <name> commit    ! finalize a pending session

Checkpoints and Rollback

configure checkpoint save <name>
rollback running-config checkpoint <name>
write memory